Blockchain with random committee selection

ABSTRACT

An example operation may include one or more of storing blockchain blocks committed to a blockchain based on a protocol executed by a current consensus committee of a blockchain network, receiving random values from the blockchain blocks which are created by nodes of the current consensus committee, randomly determining nodes of a next consensus committee of the blockchain network with respect to the current consensus committee based on the random values created by the nodes of the current consensus committee, and storing a new block to the blockchain based on a protocol based executed by the nodes of the next consensus committee.

BACKGROUND

A centralized platform stores and maintains data in a single location.This location is often a central computer, for example, a cloudcomputing environment, a web server, a mainframe computer, or the like.Information stored on a centralized platform is typically accessiblefrom multiple different points. Multiple users or client workstationscan work simultaneously on the centralized platform, for example, basedon a client/server configuration. A centralized platform is easy tomanage, maintain, and control, especially for purposes of securitybecause of its single location. Within a centralized platform, dataredundancy is minimized as a single storing place of all data alsoimplies that a given set of data only has one primary record.

SUMMARY

One example embodiment provides an apparatus that includes one or moreof a memory configured to store blockchain blocks committed to ablockchain based on a protocol executed by a current consensus committeeof a blockchain network, and a processor configured to one or more ofreceive random values from the blockchain blocks which are created bynodes of the current consensus committee, randomly determines nodes of anext consensus committee of the blockchain network with respect to thecurrent consensus committee based on the random values created by thenodes of the current consensus committee, and stores a new block to theblockchain in memory based on a protocol executed by the nodes of thenext consensus committee.

Another example embodiment provides a method that includes one or moreof storing blockchain blocks committed to a blockchain based on aprotocol executed by a current consensus committee of a blockchainnetwork, receiving random values from the blockchain blocks which arecreated by nodes of the current consensus committee, randomlydetermining nodes of a next consensus committee of the blockchainnetwork with respect to the current consensus committee based on therandom values created by the nodes of the current consensus committee,and storing a new block to the blockchain based on a protocol executedby the nodes of the next consensus committee.

A further example embodiment provides a non-transitory computer-readablemedium comprising instructions, that when read by a processor, cause theprocessor to perform one or more of storing blockchain blocks committedto a blockchain based on a protocol executed by a current consensuscommittee of a blockchain network, receiving random values from theblockchain blocks which are created by nodes of the current consensuscommittee, randomly determining nodes of a next consensus committee ofthe blockchain network with respect to the current consensus committeebased on the random values created by the nodes of the current consensuscommittee, and storing a new block to the blockchain based on a protocolexecuted by the nodes of the next consensus committee.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagram illustrating a blockchain network that uses randomcommittee selection for blockchain consensus according to exampleembodiments.

FIG. 1B is a diagram illustrating a consensus process performed by theblockchain network, according to example embodiments.

FIG. 1C is a diagram illustrating a process of storing randomcommitments to a blockchain, according to example embodiments.

FIGS. 1D and 1E are diagrams illustrating a process of receiving therandom commitments from the blockchain and determining a next consensuscommittee according to example embodiments.

FIG. 2A is a diagram illustrating an example blockchain architectureconfiguration, according to example embodiments.

FIG. 2B is a diagram illustrating a blockchain transactional flow amongnodes, according to example embodiments.

FIG. 3A is a diagram illustrating a permissioned network, according toexample embodiments.

FIG. 3B is a diagram illustrating another permissioned network,according to example embodiments.

FIG. 3C is a diagram illustrating a permissionless network, according toexample embodiments.

FIGS. 4A-4D are diagrams illustrating block metadata generated by acurrent consensus committee according to example embodiments.

FIG. 5 is a diagram illustrating a method of randomly determining a nextconsensus committee of a blockchain network according to exampleembodiments.

FIG. 6A is a diagram illustrating an example system configured toperform one or more operations described herein, according to exampleembodiments.

FIG. 6B is a diagram illustrating another example system configured toperform one or more operations described herein, according to exampleembodiments.

FIG. 6C is a diagram illustrating a further example system configured toutilize a smart contract, according to example embodiments.

FIG. 6D is a diagram illustrating yet another example system configuredto utilize a blockchain, according to example embodiments.

FIG. 7A is a diagram illustrating a process of a new block being addedto a distributed ledger, according to example embodiments.

FIG. 7B is a diagram illustrating data contents of a new data block,according to example embodiments.

FIG. 7C is a diagram illustrating a blockchain for digital content,according to example embodiments.

FIG. 7D is a diagram illustrating a block which may represent thestructure of blocks in the blockchain, according to example embodiments.

FIG. 8A is a diagram illustrating an example blockchain which storesmachine learning (artificial intelligence) data, according to exampleembodiments.

FIG. 8B is a diagram illustrating an example quantum-secure blockchain,according to example embodiments.

FIG. 9 is a diagram illustrating an example system that supports one ormore of the example embodiments.

DETAILED DESCRIPTION

It will be readily understood that the instant components, as generallydescribed and illustrated in the figures herein, may be arranged anddesigned in a wide variety of different configurations. Thus, thefollowing detailed description of the embodiments of at least one of amethod, apparatus, non-transitory computer readable medium and system,as represented in the attached figures, is not intended to limit thescope of the application as claimed but is merely representative ofselected embodiments.

The instant features, structures, or characteristics as describedthroughout this specification may be combined or removed in any suitablemanner in one or more embodiments. For example, the usage of the phrases“example embodiments”, “some embodiments”, or other similar language,throughout this specification refers to the fact that a particularfeature, structure, or characteristic described in connection with theembodiment may be included in at least one embodiment. Thus, appearancesof the phrases “example embodiments”, “in some embodiments”, “in otherembodiments”, or other similar language, throughout this specificationdo not necessarily all refer to the same group of embodiments, and thedescribed features, structures, or characteristics may be combined orremoved in any suitable manner in one or more embodiments. Further, inthe diagrams, any connection between elements can permit one-way and/ortwo-way communication even if the depicted connection is a one-way ortwo-way arrow. Also, any device depicted in the drawings can be adifferent device. For example, if a mobile device is shown sendinginformation, a wired device could also be used to send the information.

In addition, while the term “message” may have been used in thedescription of embodiments, the application may be applied to many typesof networks and data. Furthermore, while certain types of connections,messages, and signaling may be depicted in exemplary embodiments, theapplication is not limited to a certain type of connection, message, andsignaling.

Example embodiments provide methods, systems, components, non-transitorycomputer readable media, devices, and/or networks, which are configuredto randomly select member nodes of a next committee for consensus usingcommitments by member nodes of a current committee. Firstborn blocks ofnodes in the current committee can be used to commit to randomlyselecting the next committee and also store random values (e.g., randomcoefficients) that are sampled from a polynomial and stored in thefirstborn blocks. Remaining non-committee nodes can pull the firstbornblocks during a blockchain protocol and use a deterministic algorithm toverify the randomness (i.e., that randomness was used and not faked) andalso identify the member nodes of the next committee based on the storedrandom values.

In one embodiment the application utilizes a decentralized database(such as a blockchain) that is a distributed storage system, whichincludes multiple nodes that communicate with each other. Thedecentralized database includes an append-only immutable data structureresembling a distributed ledger capable of maintaining records betweenmutually untrusted parties. The untrusted parties are referred to hereinas peers or peer nodes. Each peer maintains a copy of the databaserecords and no single peer can modify the database records without aconsensus being reached among the distributed peers. For example, thepeers may execute a consensus protocol to validate blockchain storagetransactions, group the storage transactions into blocks, and build ahash chain over the blocks. This process forms the ledger by orderingthe storage transactions, as is necessary, for consistency. In variousembodiments, a permissioned and/or a permissionless blockchain can beused. In a public or permission-less blockchain, anyone can participatewithout a specific identity. Public blockchains can involve nativecryptocurrency and use consensus based on various protocols such asProof of Work (PoW). On the other hand, a permissioned blockchaindatabase provides secure interactions among a group of entities whichshare a common goal but which do not fully trust one another, such asbusinesses that exchange funds, goods, information, and the like.

This application can utilize a blockchain that operates arbitrary,programmable logic, tailored to a decentralized storage scheme andreferred to as “smart contracts” or “chaincodes.” In some cases,specialized chaincodes may exist for management functions and parameterswhich are referred to as system chaincode. The application can furtherutilize smart contracts that are trusted distributed applications whichleverage tamper-proof properties of the blockchain database and anunderlying agreement between nodes, which is referred to as anendorsement or endorsement policy. Blockchain transactions associatedwith this application can be “endorsed” before being committed to theblockchain while transactions, which are not endorsed, are disregarded.An endorsement policy allows chaincode to specify endorsers for atransaction in the form of a set of peer nodes that are necessary forendorsement. When a client sends the transaction to the peers specifiedin the endorsement policy, the transaction is executed to validate thetransaction. After validation, the transactions enter an ordering phasein which a consensus protocol is used to produce an ordered sequence ofendorsed transactions grouped into blocks.

This application can utilize nodes that are the communication entitiesof the blockchain system. A “node” may perform a logical function in thesense that multiple nodes of different types can run on the samephysical server. Nodes are grouped in trust domains and are associatedwith logical entities that control them in various ways. Nodes mayinclude different types, such as a client or submitting-client nodewhich submits a transaction-invocation to an endorser (e.g., peer), andbroadcasts transaction-proposals to an ordering service (e.g., orderingnode). Another type of node is a peer node which can receive clientsubmitted transactions, commit the transactions and maintain a state anda copy of the ledger of blockchain transactions. Peers can also have therole of an endorser, although it is not a requirement. Anordering-service-node or orderer is a node running the communicationservice for all nodes, and which implements a delivery guarantee, suchas a broadcast to each of the peer nodes in the system when committingtransactions and modifying a world state of the blockchain, which isanother name for the initial blockchain transaction which normallyincludes control and setup information.

This application can utilize a ledger that is a sequenced,tamper-resistant record of all state transitions of a blockchain. Statetransitions may result from chaincode invocations (i.e., transactions)submitted by participating parties (e.g., client nodes, ordering nodes,endorser nodes, peer nodes, etc.). Each participating party (such as apeer node) can maintain a copy of the ledger. A transaction may resultin a set of asset key-value pairs being committed to the ledger as oneor more operands, such as creates, updates, deletes, and the like. Theledger includes a blockchain (also referred to as a chain) which is usedto store an immutable, sequenced record in blocks. The ledger alsoincludes a state database which maintains a current state of theblockchain.

This application can utilize a chain that is a transaction log which isstructured as hash-linked blocks, and each block contains a sequence ofN transactions where N is equal to or greater than one. The block headerincludes a hash of the block's transactions, as well as a hash of theprior block's header. In this way, all transactions on the ledger may besequenced and cryptographically linked together. Accordingly, it is notpossible to tamper with the ledger data without breaking the hash links.A hash of a most recently added blockchain block represents everytransaction on the chain that has come before it, making it possible toensure that all peer nodes are in a consistent and trusted state. Thechain may be stored on a peer node file system (i.e., local, attachedstorage, cloud, etc.), efficiently supporting the append-only nature ofthe blockchain workload.

The current state of the immutable ledger represents the latest valuesfor all keys that are included in the chain transaction log. Since thecurrent state represents the latest key values known to a channel, it issometimes referred to as a world state. Chaincode invocations executetransactions against the current state data of the ledger. To make thesechaincode interactions efficient, the latest values of the keys may bestored in a state database. The state database may be simply an indexedview into the chain's transaction log, it can therefore be regeneratedfrom the chain at any time. The state database may automatically berecovered (or generated if needed) upon peer node startup, and beforetransactions are accepted.

A blockchain network may include many blockchain peers which each hold acopy/replica of a blockchain ledger. Consensus protocols are used by theblockchain network to ensure that the state of the blockchain ledger isconsistent across all of the blockchain peers. One algorithm that iscommonly used for consensus is practical byzantine fault tolerance(pBFT). In a pBFT consensus, one or more primary peers act as a leadpeer for the remaining peers (referred to herein as following peers orconsensus peer). Each lead peer maintains an internal state of theblockchain ledger as do the following peers.

Blockchain frameworks may implement a consensus committee which is asubset of nodes from a larger set of all nodes that are memberparticipants of a blockchain network. By only using a subset of nodesfor consensus, the amount of messages and verifications that must beperformed during block consensus can be significantly reduced. Aconsensus committee may include a lead member (e.g., selected by theother nodes of the blockchain network, a predetermined protocol, etc.),and one or more following members that also participate in the consensusprocess.

When a request to store data to the blockchain is received from aclient, the lead node creates a proposal and multicasts the proposal tothe following nodes of the consensus committee that are grouped with thelead node. Next, the following nodes share the proposal with each otherto ensure that there is an agreement on the blockchain proposal. When anagreement is reached, the following nodes (and the lead nodes) committhe blockchain proposal to their internal ledgers, and forward aresponse to the client. Furthermore, remaining non-committee nodes thatare participants in the blockchain are able to pull or otherwise receivethe blocks and store them to their respective ledgers.

FIG. 1A illustrates a process 100 of a blockchain network that usesrandom committee selection for blockchain consensus according to exampleembodiments. Referring to FIG. 1A, a current consensus committee isshown in blockchain network 110A. Here, the current consensus committeeincludes member nodes 111, 112, 113, and 114, with node 111 being thelead node. The current consensus committee may hold their position for apredetermined period of time (e.g., a predetermined number of blocks).As another example, the current consensus committee may hold theirposition until a predetermined period of time is elapsed, a request isreceived to change the committee, or some other condition (e.g.,timeout, faulty node detected, etc.)

When it is time, the current consensus committee shown in blockchainnetwork 110A switches to a next consensus committee as shown inblockchain network 110B. In the next consensus committee of theblockchain network 110B, the new committee member nodes include nodes114, 115, 116, and 117. As further described herein, the new membernodes 114, 115, 116, and 117 of the next consensus committee areselected at random based on commitments by member nodes 111, 112, 113,and 114 stored to blocks of the blockchain while the current consensuscommittee is actively in the role of consensus. That is, blocks that arecreated and stored while the current consensus committee is activelyperforming the role of the consensus committee are used toidentify/randomly the next consensus committee.

In this example, the nodes may operate based on a byzantine faulttolerance (BFT) consensus protocol. Here, the nodes of the consensuscommittee identify a primary node among them that operates as a leaderwhen data is added to the blockchain. Meanwhile, the remaining nodes ofthe committee are referred to as “followers” that participate with theleader node. The BFT consensus can work even when faulty nodes arepresent. In the examples herein, it is assumed that at most f faultynodes may exist in a blockchain network that includes n nodes, where nis equal to or greater than 3f+1. Therefore, in order for a consensus tobe ensured among the blockchain peers, at least n-f nodes must come toan agreement. The result is that a first subset of nodes 111, 112, 113,and 114 that are members of the current consensus committee are rotatedto a second subset of nodes 114, 115, 116, and 117 of a next consensuscommittee. Here, both committees include different subsets of nodes fromthe blockchain network, although in some cases the committees may bepartially overlapping in membership.

FIG. 1B illustrates a consensus process 120 performed by the currentconsensus committee shown in FIG. 1A. In this example a new block isadded to a blockchain (not shown) based on a consensus reached among thenodes 111, 112, 113, and 114 of the current consensus committee. In thisexample, the node 111 is the current lead node for the committee.However, the lead node changes over time. For example, each node 111,112, 113, and 114, may spend time as the lead node based on around-robin approach, or the like. Also, while four (4) blockchain nodeswith one lead node are shown in this example for convenience ofdescription, it should be appreciated that a blockchain network may havemany blockchain nodes including multiple lead nodes at the same timeeach serving different subsets of follower peers.

Referring to FIG. 1B, the lead node 111 may receive a request from aclient application (not shown) to store a new transaction to ablockchain. This step is omitted in the drawing. In a pre-prepare phase121, the lead node 111 may order transactions into a block and broadcastthe list of ordered transactions to the other nodes 112, 113, and 114,that are part of the current consensus committee.

Each blockchain node (112, 113, and 114) may calculate a hash code forthe newly created block which include the hashes of the transactions anda final state of the world to be added to the state database, andbroadcast a prepare message including the resulting hash to the othernodes (112, 113, and 114) in the network. Thus, the nodes may receiveprepare messages from the other nodes.

When the nodes receive a predetermined threshold of prepare messages(e.g., 2f+1), in a commit phase 123, the nodes may generate a commitmessage, sign the commit message, and transmit the commit message to theother nodes. When the nodes receive a predetermined threshold of commitmessages, the nodes may commit the block to a local copy of theblockchain which includes the chain of blocks and the update to thestate database. The other nodes of the blockchain network (non-committeemembers) may pull blocks from any of the committee members 111, 112,113, and 114 to update their own respective ledgers.

As further described herein, the current consensus committee maycontinue to produce blocks until a committee change is needed. In someembodiments, the committee may have a lower bound (i.e., a minimumnumber of blocks that the committee must produce before a committeeswitch), but no upper bound. When the minimum number of blocks have beenproduced, the committee change can occur at any time thereafter. Atwhich point, content stored within the blocks produced by the currentconsensus committee can be used by all nodes (not just the nodes thatare committee members of the current consensus committee) to detect thenodes that are to be included in the next consensus committee. Here, thenodes to be included in the next consensus committee are selectedrandomly by the nodes of the current consensus committee. In some cases,there may be an overlap in membership (i.e., a node may be both a memberof the current consensus committee and the next consensus committee). Inthis example, the node 114 is a member of both consensus committees.

FIG. 1C illustrates a process 130 of storing random commitments to ablockchain, according to example embodiments. Referring to FIG. 1C,firstborn blocks 131, 132, and 133, (i.e., blocks first produced) byeach of the respective nodes 112, 113, and 114 that are memberparticipants of the current consensus committee include commitments torandomness, that is, randomly selecting member nodes of the nextconsensus committee.

To commit to randomness, each node (e.g., nodes 112, 113, and 114)selects f random polynomial coefficients {a_0, a_1, . . . , a_f} whereeach coefficient is selected uniformly at random from a range (0,q)where q is the order (order—number of elements in group) of the group G,as shown in the equation below.

Commit:

-   -   Sample a random polynomial p(x)=Σ_(j=0) ^(f)α_(j)·x_(j).    -   Commit to its coefficients {g^(α) ^(j) }_(j=0) ^(f).

Then, each coefficient is committed by performing an operation thatinvolves a group generator g and the coefficient. If the group G is amultiplicative group, then the operation is exponentiation. If the groupG is an additive group (e.g., an Elliptic Curve group) then theoperation is multiplication. In this example, a commitment, incryptography, is an operation that hides the input. The assumption ofthe group G is that if the coefficient is sampled from a range that isvery big (in products it may be a range that has around 2{circumflexover ( )}255 elements) then a party observing the commitment cannotguess what the coefficient is. After L−1 blocks are produced, thecommittee may produce a single block 134 that reveals the randomness.

In this example, the commitment includes both hiding and binding. Inparticular, from looking at the commitment, no one can figure out aninput used to produce the commitment (i.e., it is hidden). Furthermore,the node that committed to the input and produced the commitment, cannotfind a different input that yields the commitment output (i.e., it isbinding). Even if such exists, it should not be able to find one. Anexample for a commitment is for instance, if there is a random string xof 256 bits, and then hash it via a hash function such as SHA256, no onecan find the pre-image x and also the committer cannot find a differentstring x′ such that its hash is the hash of x. In the exampleembodiments, nodes may use something else (exponentiation/multiplicationof a group generator g by an exponent) because it incorporates nicelywith zero knowledge proofs.

In the commit phase, in the first L−1 blocks, each node 112, 113, and114, in its firstborn block 131, 132, and 133, commits to thecoefficients (that comprise a polynomial P(x)) and also encryptsevaluations (P(x=i)) of the polynomial with each party's public key. Italso creates a zero knowledge proof (ZKP) which the remaining nodescheck that the node didn't cheat as shown below.

Commit:

-   -   Sample a random polynomial p(x)=Σ_(j=0) ^(f)α_(j)·x_(j)    -   Commit to its coefficients {g^(α) ^(j) }_(j=0) ^(f).    -   Encrypt evaluations of h^(p(i)) for each party i∈{1, . . . , n}.    -   Create ZKP of correctness of encryption.

Then, when revealing the randomness in the last block 134 of thecommittee, the lead node 111 does not actually reveal the coefficientsa_0, a_1, . . . a_f but instead simply constructs a random number thatis impossible to construct before the last block 134 is created. Here,after L−1 blocks are produced, the committee (e.g., lead node 111) mayproduce the last block 134 to reveal the randomness of all f+1 firstbornblocks 131, 132, and 133. For example, followers included in theprotocol can message for agreement on a block with reconstructions ofrandomness. Finally, the randomness for the next committee is set.

To reconstruct, each party i decrypts the evaluations given to it by allparties in the commit phase (including itself) and sends them to partiesalong with a zero knowledge proof that ensures it decrypted correctly asshown below.

Reconstruct: {(C_(i), E_(i))}_(i=1) ^(f+1):

-   -   Each party i decrypts its evaluation h^(p(i)) and sends it along        with a ZKP for correctness of decryption.

Then, all parties reconstruct h{circumflex over ( )}{a_0} for each partyand then they concatenate all these together (from all parties).

To produce the commits by the nodes 112, 113, and 114, the nodes 112,113, and 114 can piggyback on the blocks disseminated during ablockchain protocol of which the current consensus committee isresponsible for performing consensus. Here, the commits can be sent viathe pre-prepare messages (i.e., pre-prepare stage 121 shown in FIG. 1B)of the consensus protocol. Furthermore, to reveal the randomness, thelead node 111 may piggyback on the last message of the consensusprotocol (i.e., in the commit stage 123 shown in FIG. 1 ), having eachnode include reconstruction shares (decryptions+zero knowledge proofs).By piggybacking the reconstruction of the randomness in the last messageof the last block 134, when the block 134 is created (right before thefirst step—pre-prepare) even the lead node 111 that proposes that block,doesn't know the randomness, hence doesn't know the next committee.

The commit messages of the nodes 112, 113, and 114, may be signed by thenodes 112, 113, and 114, and the signatures on the block are collectedin this manner, and thus indirectly also sign over the reconstructionshares. This means that every node that collects the last committeeblock 134, and its corresponding 2f+1 signatures, can determine the nextcommittee.

Once the committee nodes assemble the last block 134, the rest of thenodes (non-committee members) can pull it, and then they can compute thenext committee because they collect 2f+1 signatures where each signaturecontains reconstruction shares of that node that produced the signature.So, each node outside of the committee that receives the last committeeblock 134 and its corresponding signatures, can also reconstruct therandomness, and compute the next committee in the same manner that thenodes in the committee do. The next consensus committee takes over bystarting the consensus protocol for successive blocks. Each node in theprevious committee can continue to participate in the consensus protocolif it is randomly selected for the next committee. Otherwise, the nodein the previous committee ceases participating the consensus protocoland starts being a passive block puller from nodes that are in the newcommittee.

A verification process similar to a public verifiable secret sharingscheme (PVSS) may be used to verify that the lead node provided theshares in a correct manner. The PVSS scheme is a scheme where a dealer(in this case, the lead node 111) secret shares a value to multipleparties and then the parties can verify that the dealer did the sharedistribution in a sound manner, and also when the value isreconstructed, it is possible to know if it is reconstructed correctly,and if not, who is cheating. In this case, a typical PVSS scheme is notperformed because the secret that is secret shared, the a₀ coefficientof the polynomial is never actually reconstructed, but instead thesecret that is reconstructed is h{circumflex over ( )}{a₀}. Here, thenodes just need the reconstructed value to be random, not to have anyspecial semantic meaning. The shares come from each leader node thatcreate a random polynomial by picking f+1 random coefficients a₀, a₁, .. . a_(f) as explained above. Furthermore, the secret is reconstructed.Each party decrypts the encryption of its share and broadcasts thisdecryption along with a zero knowledge proof that proves correctdecryption. Then, given enough (f+1) decryptions, any party canreconstruct the secret (the random h{circumflex over ( )}{a₀}).

FIGS. 1D and 1E illustrate processes 140 and 150 of receiving the randomcommitments from the blockchain and determining a next consensuscommittee according to example embodiments. For simplicity, only thenodes of a next committee (i.e., nodes 114, 115, 116, and 117) are shownin the example of FIG. 1D, but it should be appreciated that theprocesses described herein can be performed by all nodes of theblockchain network including the current consensus committee, the nextconsensus committee, and any nodes that are not part of the consensuscommittees but part of the blockchain network. Referring to FIG. 1D, thenodes 114, 115, 116, and 117 pull the last block 134 from the currentcommittee which includes a notification (further described in theexample of FIG. 4D) that a new committee change is going to occur. Inresponse, the nodes 114, 115, 116, and 117 access the blockchain andread the content of the firstborn blocks 131, 132, and 133 of the nodes112, 113, and 114, and detect the random values (e.g., randomcoefficients) stored therein. The nodes 114, 115, 116, and 117, canperform a common reconstruction process from the random values to arriveat the next committee.

An example scenario of a committee selection process may include: Thenodes may need f+1 commitments (where f is the upper bound for maliciousand colluding nodes). In each such a commitment, a node (the committernode) may do two things: (a) including committing to randomness and (b)secret sharing the randomness it committed to, to n parts (where n isthe number of parties and n=3f+1) and encrypts each part with eachcorresponding public key of each node. Both of these processes (a) and(b) may be performed together. Performing (a)+(b) is done as follows:

First, a random polynomial of degree f may be sampled as shown in theequation below:

P(x)=a ₀ +a ₁ x+a ₂ x ² + . . . +a _(f) x ^(f)

To sample a random polynomial, a node selects the coefficients a₀, a₁,a₂, . . . a_(f) uniformly at random from a range between 0 and q where qis the order (size) of the group. Next, to commit to each coefficient,the node takes a group generator g and exponentiates g to the power ofeach coefficient: g^(a0), g^(a1), g^(a2), . . . g^(af) (in an Ellipticcurve group this is multiply instead: g*a₀, g*a₁, g*a₂, . . . g*a_(f)).Now, the cryptographic assumption is that by looking at all commitments,it is impossible to compute a₀ which is the “secret” that is committedto by the node. To secret share the randomness committee, the node takesthe polynomial P(x)=a₀+a₁x+a₂x²+ . . . +a_(f)x^(f) and evaluates it atpoints x=1, x=2, x=3 . . . x=n. More specifically, the node can computeP(i)=a₀+a₁*i+a₂i²+ . . . +a_(f)*i^(f) for i=1 to i=n. Each such apolynomial evaluation P(i) is then “encrypted” with the public key ofeach node, resulting in {Enc(P(1)), Enc(P(2)), . . . Enc(P(n))}. Here,the public keys of the nodes are selected. Also, a node has a generatorh (different from g) such that no one knows what is the relation betweenh and g. In this example, a private key of a node i is denoted by x_(i).The public key of node i is h^(xi) (and in Elliptic curves, h*x_(i)). Toencrypt an integer r, the node can take h^(xi) and compute(h^(xi))^(r)(and in Elliptic curves, r*x_(i)*h. Here, node i can yieldh^(r) (r*h for Elliptic curves) from the encryption of r by taking(h^(xi))^(r) and exponentiating by the inverse of x_(i) in Z_(q) whichonly that node knows, to get ((h^(xi))^(r)){circumflex over ( )}(x_(i))⁻¹=(h^(r)){circumflex over ( )}((x_(i))⁻¹*(x_(i)))=(h^(r)) (inthe Elliptic curve case it's r*x_(i)*h*(x_(i))⁻¹=r*h).

Accordingly, each node, when it commits to randomness a₀, it encryptsevaluations of the polynomial P(x) for every node i:(h^(x1))^(P(1))·(h^(x2))^(P(2)), . . . , (h^(xn))^(P(n)). Furthermore,zero knowledge proofs ensure that the encryption and the evaluationshave been computed correctly.

To generate node identifiers for the next consensus committee, the nodesmay perform various processes. In this case, each node has encryptionsof evaluations (h^(x1))^(P(1))·(h^(x2))^(P(2)), . . . , (h^(xn))^(P(n))made by a specific node i and wants each node to compute (h^(a0)) whichwill be the randomness contributed by node i. When making the last blockof the committee, each node j will decrypt its share (h^(xj))^(P(j)) andsend all nodes the decryption h^(P(j)) and a zero knowledge proof thatensures the decryption indeed matches the encryption. Here, all nodesmay compute h^(a0) from h^(P(1)), h^(P(2)), . . . , h^(P(n)).

Each node collects 2f+1 such decryptions, and it is assumed that thereare at least f+1 honest nodes that sent decryptions (and these nodes canbe located). Since all decryptions are accompanied by zero knowledgeproofs that the previous encryption (h^(xj))^(P(j)) matches thedecryption (h^(xj))^(P(j)), thus every decryption that has acorresponding zero knowledge proof that passes verification, has sent a“correct” decryption and it is safe to use it. Here, with such f+1decryptions h^(P(1)), h^(P(2)), . . . , h^(P(f+1)), each node cancompute h^(a0), the shared randomness contributed by node i. In thiscase, even though the coefficients are in the exponents h^(P(1)),h^(P(2)), . . . , h^(P(f+1)), the nodes can still use Lagrangeinterpolation to compute h^(a0), which may assign node identifiernumbers to the formula of Lagrange interpolation.

In this example, there are f+1 committing nodes, and all nodes canperform a reconstruction of h^(a0), for every node that committed amongthe first f+1 committing nodes and thus have f+1 different randomvalues: h^(a0) ₁, h^(a0) ₂, . . . , h^(a0) _(f+1). Furthermore, eachnode can now “mash” or otherwise combine these random values together,by hashing them with a cryptographic hash function: s=H(h^(a0) ₁∥h^(a0)₂∥ . . . ∥h^(a0) _(f+1)). The hash function makes it that if at least asingle honest node contribute unbiased randomness, the result is alsounbiased randomness. Referring to FIG. 1E, each node may construct arandom seed 160 using this process by retrieving random values 141, 142,and 143, from the blocks 131, 132, and 133. The random seed 160 can thenbe used to select the nodes of the next committee. As an example of oneembodiment, each node may instantiate a Pseudo-Random Number Generator(PRNG) with the random seed 160 and then repeatedly select n numbers161, 162, 163, and 164, without repetition where each number correspondsto an “index” of the node in the total list of nodes in the network. Aninterpreter 170 may convert each of the numbers 161, 162, 163, and 164into a corresponding node identifier of a node as shown in nodeidentifiers 172.

In some embodiments, the network may maximize liveness in a selectedcommittee. For example, all nodes outside of the current consensuscommittee can periodically send heartbeat messages to nodes inside thecommittee. During agreement on a block, each node may also sendidentifiers of nodes which it suspects are faulty with its commitmessages in the commit stage (i.e., commit stage 123 in FIG. 1 i ). Anode is not allowed to be added to the next consensus committee if atleast f+1 nodes suspect it to be faulty at the time of agreeing on thelast block.

When no node misbehaved or crashed during the current committee'sconsensus process, the committee may still keep liveness as a priority.For example, at least K random nodes may be removed and K new randomnodes may be introduced to the committee. Added nodes can be elected tothe next committee but may not be used to change a current committee.Furthermore, removing a node from a current committee makes it unable tobroadcast its decryptions when the committee reaches the end of itslife. To address this, removal of nodes may be prevented, or, sincethere are n=3f+1 nodes in total, and the system only needs f+1 nodes toselect the next committee, the system may allow up to f nodes to beremoved from the membership of the current committee.

When a committee rotation occurs, the transactions held by the currentcommittee and awaiting storage on the blockchain (e.g., in a transactionpool, queue, etc.) may be forwarded to the member nodes of the newcommittee.

FIG. 2A illustrates a blockchain architecture configuration 200,according to example embodiments. Referring to FIG. 2A, the blockchainarchitecture 200 may include certain blockchain elements, for example, agroup of blockchain nodes 202. The blockchain nodes 202 may include oneor more nodes 204-210 (these four nodes are depicted by example only).These nodes participate in a number of activities, such as blockchaintransaction addition and validation process (consensus). One or more ofthe blockchain nodes 204-210 may endorse transactions based onendorsement policy and may provide an ordering service for allblockchain nodes in the architecture 200. A blockchain node may initiatea blockchain authentication and seek to write to a blockchain immutableledger stored in blockchain layer 216, a copy of which may also bestored on the underpinning physical infrastructure 214. The blockchainconfiguration may include one or more applications 224 which are linkedto application programming interfaces (APIs) 222 to access and executestored program/application code 220 (e.g., chaincode, smart contracts,etc.) which can be created according to a customized configurationsought by participants and can maintain their own state, control theirown assets, and receive external information. This can be deployed as atransaction and installed, via appending to the distributed ledger, onall blockchain nodes 204-210.

The blockchain base or platform 212 may include various layers ofblockchain data, services (e.g., cryptographic trust services, virtualexecution environment, etc.), and underpinning physical computerinfrastructure that may be used to receive and store new transactionsand provide access to auditors which are seeking to access data entries.The blockchain layer 216 may expose an interface that provides access tothe virtual execution environment necessary to process the program codeand engage the physical infrastructure 214. Cryptographic trust services218 may be used to verify transactions such as asset exchangetransactions and keep information private.

The blockchain architecture configuration of FIG. 2A may process andexecute program/application code 220 via one or more interfaces exposed,and services provided, by blockchain platform 212. The code 220 maycontrol blockchain assets. For example, the code 220 can store andtransfer data, and may be executed by nodes 204-210 in the form of asmart contract and associated chaincode with conditions or other codeelements subject to its execution. As a non-limiting example, smartcontracts may be created to execute reminders, updates, and/or othernotifications subject to the changes, updates, etc. The smart contractscan themselves be used to identify rules associated with authorizationand access requirements and usage of the ledger. For example, the smartcontract (or chaincode executing the logic of the smart contract) mayread blockchain data 226 which may be processed by one or moreprocessing entities (e.g., virtual machines) included in the blockchainlayer 216 to generate results 228 including data to be written to theblockchain. The physical infrastructure 214 may be utilized to retrieveany of the data or information described herein.

A smart contract may be created via a high-level application andprogramming language, and then written to a block in the blockchain. Thesmart contract may include executable code which is registered, stored,and/or replicated with a blockchain (e.g., distributed network ofblockchain peers). A transaction is an execution of the smart contractcode which can be performed in response to conditions associated withthe smart contract being satisfied. The executing of the smart contractmay trigger a trusted modification(s) to a state of a digital blockchainledger. The modification(s) to the blockchain ledger caused by the smartcontract execution may be automatically replicated throughout thedistributed network of blockchain peers through one or more consensusprotocols.

The smart contract may write data to the blockchain in the format ofkey-value pairs. Furthermore, the smart contract code can read thevalues stored in a blockchain and use them in application operations.The smart contract code can write the output of various logic operationsinto one or more blocks within the blockchain. The code may be used tocreate a temporary data structure in a virtual machine or othercomputing platform. Data written to the blockchain can be public and/orcan be encrypted and maintained as private. The temporary data that isused/generated by the smart contract is held in memory by the suppliedexecution environment, then deleted once the data needed for theblockchain is identified.

A chaincode may include the code interpretation (e.g., the logic) of asmart contract. For example, the chaincode may include a packaged anddeployable version of the logic within the smart contract. As describedherein, the chaincode may be program code deployed on a computingnetwork, where it is executed and validated by chain validators togetherduring a consensus process. The chaincode may receive a hash andretrieve from the blockchain a hash associated with the data templatecreated by use of a previously stored feature extractor. If the hashesof the hash identifier and the hash created from the stored identifiertemplate data match, then the chaincode sends an authorization key tothe requested service. The chaincode may write to the blockchain dataassociated with the cryptographic details.

FIG. 2B illustrates an example of a blockchain transactional flow 250between nodes of the blockchain in accordance with an exampleembodiment. Referring to FIG. 2B, the transaction flow may include aclient node 260 transmitting a transaction proposal 291 to an endorsingpeer node 281. The endorsing peer 281 may verify the client signatureand execute a chaincode function to initiate the transaction. The outputmay include the chaincode results, a set of key/value versions that wereread in the chaincode (read set), and the set of keys/values that werewritten in chaincode (write set). Here, the endorsing peer 281 maydetermine whether or not to endorse the transaction proposal. Theproposal response 292 is sent back to the client 260 along with anendorsement signature, if approved. The client 260 assembles theendorsements into a transaction payload 293 and broadcasts it to anordering service node 284. The ordering service node 284 then deliversordered transactions as blocks to all peers 281-283 on a channel. Beforecommittal to the blockchain, each peer 281-283 may validate thetransaction. For example, the peers may check the endorsement policy toensure that the correct allotment of the specified peers have signed theresults and authenticated the signatures against the transaction payload293.

Referring again to FIG. 2B, the client node initiates the transaction291 by constructing and sending a request to the peer node 281, which isan endorser. The client 260 may include an application leveraging asupported software development kit (SDK), which utilizes an availableAPI to generate a transaction proposal. The proposal is a request toinvoke a chaincode function so that data can be read and/or written tothe ledger (i.e., write new key value pairs for the assets). The SDK mayserve as a shim to package the transaction proposal into a properlyarchitected format (e.g., protocol buffer over a remote procedure call(RPC)) and take the client's cryptographic credentials to produce aunique signature for the transaction proposal.

In response, the endorsing peer node 281 may verify (a) that thetransaction proposal is well formed, (b) the transaction has not beensubmitted already in the past (replay-attack protection), (c) thesignature is valid, and (d) that the submitter (client 260, in theexample) is properly authorized to perform the proposed operation onthat channel. The endorsing peer node 281 may take the transactionproposal inputs as arguments to the invoked chaincode function. Thechaincode is then executed against a current state database to producetransaction results including a response value, read set, and write set.However, no updates are made to the ledger at this point. In 292, theset of values, along with the endorsing peer node's 281 signature ispassed back as a proposal response 292 to the SDK of the client 260which parses the payload for the application to consume.

In response, the application of the client 260 inspects/verifies theendorsing peers signatures and compares the proposal responses todetermine if the proposal response is the same. If the chaincode onlyqueried the ledger, the application would inspect the query response andwould typically not submit the transaction to the ordering node service284. If the client application intends to submit the transaction to theordering node service 284 to update the ledger, the applicationdetermines if the specified endorsement policy has been fulfilled beforesubmitting (i.e., did all peer nodes necessary for the transactionendorse the transaction). Here, the client may include only one ofmultiple parties to the transaction. In this case, each client may havetheir own endorsing node, and each endorsing node will need to endorsethe transaction. The architecture is such that even if an applicationselects not to inspect responses or otherwise forwards an unendorsedtransaction, the endorsement policy will still be enforced by peers andupheld at the commit validation phase.

After successful inspection, in step 293 the client 260 assemblesendorsements into a transaction proposal and broadcasts the transactionproposal and response within a transaction message to the ordering node284. The transaction may contain the read/write sets, the endorsingpeers signatures and a channel ID. The ordering node 284 does not needto inspect the entire content of a transaction in order to perform itsoperation, instead the ordering node 284 may simply receive transactionsfrom all channels in the network, order them chronologically by channel,and create blocks of transactions per channel.

The blocks are delivered from the ordering node 284 to all peer nodes281-283 on the channel. The data section within the block may bevalidated to ensure an endorsement policy is fulfilled and to ensurethat there have been no changes to ledger state for read set variablessince the read set was generated by the transaction execution.Furthermore, in step 295 each peer node 281-283 appends the block to thechannel's chain, and for each valid transaction the write sets arecommitted to current state database. An event may be emitted, to notifythe client application that the transaction (invocation) has beenimmutably appended to the chain, as well as to notify whether thetransaction was validated or invalidated.

FIG. 3A illustrates an example of a permissioned blockchain network 300,which features a distributed, decentralized peer-to-peer architecture.In this example, a blockchain user 302 may initiate a transaction to thepermissioned blockchain 304. In this example, the transaction can be adeploy, invoke, or query, and may be issued through a client-sideapplication leveraging an SDK, directly through an API, etc. Networksmay provide access to a regulator 306, such as an auditor. A blockchainnetwork operator 308 manages member permissions, such as enrolling theregulator 306 as an “auditor” and the blockchain user 302 as a “client”.An auditor could be restricted only to querying the ledger whereas aclient could be authorized to deploy, invoke, and query certain types ofchaincode.

A blockchain developer 310 can write chaincode and client-sideapplications. The blockchain developer 310 can deploy chaincode directlyto the network through an interface. To include credentials from atraditional data source 312 in chaincode, the developer 310 could use anout-of-band connection to access the data. In this example, theblockchain user 302 connects to the permissioned blockchain 304 througha peer node 314. Before proceeding with any transactions, the peer node314 retrieves the user's enrollment and transaction certificates from acertificate authority 316, which manages user roles and permissions. Insome cases, blockchain users must possess these digital certificates inorder to transact on the permissioned blockchain 304. Meanwhile, a userattempting to utilize chaincode may be required to verify theircredentials on the traditional data source 312. To confirm the user'sauthorization, chaincode can use an out-of-band connection to this datathrough a traditional processing platform 318.

FIG. 3B illustrates another example of a permissioned blockchain network320, which features a distributed, decentralized peer-to-peerarchitecture. In this example, a blockchain user 322 may submit atransaction to the permissioned blockchain 324. In this example, thetransaction can be a deploy, invoke, or query, and may be issued througha client-side application leveraging an SDK, directly through an API,etc. Networks may provide access to a regulator 326, such as an auditor.A blockchain network operator 328 manages member permissions, such asenrolling the regulator 326 as an “auditor” and the blockchain user 322as a “client”. An auditor could be restricted only to querying theledger whereas a client could be authorized to deploy, invoke, and querycertain types of chaincode.

A blockchain developer 330 writes chaincode and client-sideapplications. The blockchain developer 330 can deploy chaincode directlyto the network through an interface. To include credentials from atraditional data source 332 in chaincode, the developer 330 could use anout-of-band connection to access the data. In this example, theblockchain user 322 connects to the network through a peer node 334.Before proceeding with any transactions, the peer node 334 retrieves theuser's enrollment and transaction certificates from the certificateauthority 336. In some cases, blockchain users must possess thesedigital certificates in order to transact on the permissioned blockchain324. Meanwhile, a user attempting to utilize chaincode may be requiredto verify their credentials on the traditional data source 332. Toconfirm the user's authorization, chaincode can use an out-of-bandconnection to this data through a traditional processing platform 338.

In some embodiments, the blockchain herein may be a permissionlessblockchain. In contrast with permissioned blockchains which requirepermission to join, anyone can join a permissionless blockchain. Forexample, to join a permissionless blockchain a user may create apersonal address and begin interacting with the network, by submittingtransactions, and hence adding entries to the ledger. Additionally, allparties have the choice of running a node on the system and employingthe mining protocols to help verify transactions.

FIG. 3C illustrates a process 350 of a transaction being processed by apermissionless blockchain 352 including a plurality of nodes 354. Asender 356 desires to send payment or some other form of value (e.g., adeed, medical records, a contract, a good, a service, or any other assetthat can be encapsulated in a digital record) to a recipient 358 via thepermissionless blockchain 352. In one embodiment, each of the senderdevice 356 and the recipient device 358 may have digital wallets(associated with the blockchain 352) that provide user interfacecontrols and a display of transaction parameters. In response, thetransaction is broadcast throughout the blockchain 352 to the nodes 354.Depending on the blockchain's 352 network parameters the nodes verify360 the transaction based on rules (which may be pre-defined ordynamically allocated) established by the permissionless blockchain 352creators. For example, this may include verifying identities of theparties involved, etc. The transaction may be verified immediately or itmay be placed in a queue with other transactions and the nodes 354determine if the transactions are valid based on a set of network rules.

In structure 362, valid transactions are formed into a block and sealedwith a lock (hash). This process may be performed by mining nodes amongthe nodes 354. Mining nodes may utilize additional software specificallyfor mining and creating blocks for the permissionless blockchain 352.Each block may be identified by a hash (e.g., 256 bit number, etc.)created using an algorithm agreed upon by the network. Each block mayinclude a header, a pointer or reference to a hash of a previous block'sheader in the chain, and a group of valid transactions. The reference tothe previous block's hash is associated with the creation of the secureindependent chain of blocks.

Before blocks can be added to the blockchain, the blocks must bevalidated. Validation for the permissionless blockchain 352 may includea proof-of-work (PoW) which is a solution to a puzzle derived from theblock's header. Although not shown in the example of FIG. 3C, anotherprocess for validating a block is proof-of-stake. Unlike theproof-of-work, where the algorithm rewards miners that solvemathematical problems, with the proof of stake, a creator of a new blockis chosen in a deterministic way, depending on its wealth, also definedas “stake.” Then, a similar proof is performed by the selected/chosennode.

With mining 364, nodes try to solve the block by making incrementalchanges to one variable until the solution satisfies a network-widetarget. This creates the PoW thereby ensuring correct answers. In otherwords, a potential solution must prove that computing resources weredrained in solving the problem. In some types of permissionlessblockchains, miners may be rewarded with value (e.g., coins, etc.) forcorrectly mining a block.

Here, the PoW process, alongside the chaining of blocks, makesmodifications of the blockchain extremely difficult, as an attacker mustmodify all subsequent blocks in order for the modifications of one blockto be accepted. Furthermore, as new blocks are mined, the difficulty ofmodifying a block increases, and the number of subsequent blocksincreases. With distribution 366, the successfully validated block isdistributed through the permissionless blockchain 352 and all nodes 354add the block to a majority chain which is the permissionlessblockchain's 352 auditable ledger. Furthermore, the value in thetransaction submitted by the sender 356 is deposited or otherwisetransferred to the digital wallet of the recipient device 358.

FIGS. 4A-4D illustrate examples of block metadata generated by a currentconsensus committee according to example embodiments. In the exampleembodiments, any node can determine the new committee members byreconstructing the commitments of the members of the current committeewhich are stored on the blockchain. In some embodiments, the commitmentsmay be stored in a metadata structure of the blockchain block.

FIG. 4A illustrates a process 400A of adding a block 410 to a blockchainwhich includes a genesis block (block 0). In this example, the systemhas four committee members, so n=4 and f=1 because f=(n−1)/3. Initially,block metadata is empty. The block 410 is the firstborn block producedby a node 1 in the current committee. As shown in FIG. 4A, the block 410includes metadata 411 which now includes a raw state which is the blockdata in raw form, identifiers of committee nodes that have committed torandomness, a genesis block identifier, and a committee size which inthis example is 4 nodes.

FIG. 4B illustrates a process 400B of adding a block 420 to theblockchain which now includes three blocks (0, 1, and 2). Block 420 isthe firstborn block of node 2 that is a member of the committee. As aresult, the metadata 422 includes identifiers of both the first andsecond committer nodes which is equal to f+1 since f=1. In this example,there are now enough committers that have committed to randomness tosatisfy a change policy of the example and reconstruct the randomness.Thus, a final state index field is added to the metadata 421 andidentifies that enough committers have committed to randomness.

FIG. 4C illustrates a process 400C of adding blocks 430 and 440 to theblockchain. Here, the blocks 430 and 440 include metadata 431 and 441,respectively, which does not change with respect to the metadata 421 ofblock 420. FIG. 4D illustrates a process 400D in which a new block 450is added to the blockchain and the lead node recognizes that a committeechange is now to be performed. That is, the current consensus committeeis to be rotated to the next consensus committee. In this example, theblock metadata 452 includes a notification of the shift (i.e.,CommitteeShiftAt: 5), and identifiers of the current committee membersat the time of the shift (i.e., CommitteeAtShift: [1, 2, 3, 4]). Thisnotification informs the nodes that a new committee is ready and thatsuch data can be collected from the blocks of the committers [1, 2].

Although not shown, the next committee can be determined prior to block6 being generated and stored on the blockchain. Here, each node of theblockchain network looks at the CommitteeShiftAt value (block number 5)and fetches that block 450 from the blockchain. Next, the node looks atthe FinalStateIndex of block 450 (block 5) which points to block 2.Here, the node can retrieve the metadata 422 of block 420 to get its twopersisted blobs of commitments and encrypted shares. Then, the node canreconstruct shares (decryptions of encrypted shares, and ZKPs) and thensimulate what happened at the committee change at block 5 to determinethe new committee members starting from block 6 onward until the nextcommittee change.

FIG. 5 illustrates a method 500 of randomly determining a next consensuscommittee of a blockchain network according to example embodiments. Forexample, the method 500 may be performed by a blockchain nodeparticipating in a consensus protocol. The blockchain node may beimplemented via a web server, a cloud platform, a user device, a virtualmachine, or the like. Referring to FIG. 5 , in 510, the method mayinclude storing blockchain blocks committed to a blockchain based on aprotocol executed by a current consensus committee of a blockchainnetwork. Here, the blockchain may be shared among both committee membernodes and non-committee member nodes of the blockchain network.

In 520, the method may include receiving random values from theblockchain blocks which are created by nodes of the current consensuscommittee. In 530, the method may include randomly determining nodes ofa next consensus committee of the blockchain network with respect to thecurrent consensus committee based on the random values created by thenodes of the current consensus committee. In 540, the method may includestoring a new block to the blockchain based on a protocol executed bythe nodes of the next consensus committee.

In some embodiments, the current consensus committee and the nextconsensus committee may include different respective subsets of nodesfrom among a larger set of nodes included in the blockchain network. Insome embodiments, the blockchain blocks may include firstborn blockscreated by the nodes of the current consensus committee. In someembodiments, the method may further include detecting a committee changenotification within a last block produced by the current consensuscommittee, wherein the randomly determining is performed in response tothe detecting. In some embodiments, the random values may includerandomly sampled coefficients from a polynomial equation.

In some embodiments, the random values are encrypted, and the receivingmay further include receiving zero-knowledge proofs (ZKPs) from thenodes of the current consensus committee proving correctness of theencryption of the random values. In some embodiments, the randomlydetermining may include combining the random values created by the nodesof the current consensus committee into a random seed, and mappingsegments of the random seed to node identifiers of the nodes in the nextconsensus committee. In some embodiments, the receiving the randomvalues may include receiving the random values piggybacked viapre-prepare messages, respectively, of the nodes of the currentconsensus committee.

FIG. 6A illustrates an example system 600 that includes a physicalinfrastructure 610 configured to perform various operations according toexample embodiments. Referring to FIG. 6A, the physical infrastructure610 includes a module 612 and a module 614. The module 614 includes ablockchain 620 and a smart contract 630 (which may reside on theblockchain 620), that may execute any of the operational steps 608 (inmodule 612) included in any of the example embodiments. Thesteps/operations 608 may include one or more of the embodimentsdescribed or depicted and may represent output or written informationthat is written or read from one or more smart contracts 630 and/orblockchains 620. The physical infrastructure 610, the module 612, andthe module 614 may include one or more computers, servers, processors,memories, and/or wireless communication devices. Further, the module 612and the module 614 may be a same module.

FIG. 6B illustrates another example system 640 configured to performvarious operations according to example embodiments. Referring to FIG.6B, the system 640 includes a module 612 and a module 614. The module614 includes a blockchain 620 and a smart contract 630 (which may resideon the blockchain 620), that may execute any of the operational steps608 (in module 612) included in any of the example embodiments. Thesteps/operations 608 may include one or more of the embodimentsdescribed or depicted and may represent output or written informationthat is written or read from one or more smart contracts 630 and/orblockchains 620. The physical infrastructure 610, the module 612, andthe module 614 may include one or more computers, servers, processors,memories, and/or wireless communication devices. Further, the module 612and the module 614 may be a same module.

FIG. 6C illustrates an example system configured to utilize a smartcontract configuration among contracting parties and a mediating serverconfigured to enforce the smart contract terms on the blockchainaccording to example embodiments. Referring to FIG. 6C, theconfiguration 650 may represent a communication session, an assettransfer session or a process or procedure that is driven by a smartcontract 630 which explicitly identifies one or more user devices 652and/or 656. The execution, operations and results of the smart contractexecution may be managed by a server 654. Content of the smart contract630 may require digital signatures by one or more of the entities 652and 656 which are parties to the smart contract transaction. The resultsof the smart contract execution may be written to a blockchain 620 as ablockchain transaction. The smart contract 630 resides on the blockchain620 which may reside on one or more computers, servers, processors,memories, and/or wireless communication devices.

FIG. 6D illustrates a system 660 including a blockchain, according toexample embodiments. Referring to the example of FIG. 6D, an applicationprogramming interface (API) gateway 662 provides a common interface foraccessing blockchain logic (e.g., smart contract 630 or other chaincode)and data (e.g., distributed ledger, etc.). In this example, the APIgateway 662 is a common interface for performing transactions (invoke,queries, etc.) on the blockchain by connecting one or more entities 652and 656 to a blockchain peer (i.e., server 654). Here, the server 654 isa blockchain network peer component that holds a copy of the world stateand a distributed ledger allowing clients 652 and 656 to query data onthe world state as well as submit transactions into the blockchainnetwork where, depending on the smart contract 630 and endorsementpolicy, endorsing peers will run the smart contracts 630.

The above embodiments may be implemented in hardware, in a computerprogram executed by a processor, in firmware, or in a combination of theabove. A computer program may be embodied on a computer readable medium,such as a storage medium. For example, a computer program may reside inrandom access memory (“RAM”), flash memory, read-only memory (“ROM”),erasable programmable read-only memory (“EPROM”), electrically erasableprogrammable read-only memory (“EEPROM”), registers, hard disk, aremovable disk, a compact disk read-only memory (“CD-ROM”), or any otherform of storage medium known in the art.

An exemplary storage medium may be coupled to the processor such thatthe processor may read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anapplication specific integrated circuit (“ASIC”). In the alternative,the processor and the storage medium may reside as discrete components.

FIG. 7A illustrates a process 700 of a new block being added to adistributed ledger 720, according to example embodiments, and FIG. 7Billustrates contents of a new data block structure 730 for blockchain,according to example embodiments. Referring to FIG. 7A, clients (notshown) may submit transactions to blockchain nodes 711, 712, and/or 713.Clients may be instructions received from any source to enact activityon the blockchain 720. As an example, clients may be applications thatact on behalf of a requester, such as a device, person or entity topropose transactions for the blockchain. The plurality of blockchainpeers (e.g., blockchain nodes 711, 712, and 713) may maintain a state ofthe blockchain network and a copy of the distributed ledger 720.Different types of blockchain nodes/peers may be present in theblockchain network including endorsing peers which simulate and endorsetransactions proposed by clients and committing peers which verifyendorsements, validate transactions, and commit transactions to thedistributed ledger 720. In this example, the blockchain nodes 711, 712,and 713 may perform the role of endorser node, committer node, or both.

The distributed ledger 720 includes a blockchain which stores immutable,sequenced records in blocks, and a state database 724 (current worldstate) maintaining a current state of the blockchain 722. Onedistributed ledger 720 may exist per channel and each peer maintains itsown copy of the distributed ledger 720 for each channel of which theyare a member. The blockchain 722 is a transaction log, structured ashash-linked blocks where each block contains a sequence of Ntransactions. Blocks may include various components such as shown inFIG. 7B. The linking of the blocks (shown by arrows in FIG. 7A) may begenerated by adding a hash of a prior block's header within a blockheader of a current block. In this way, all transactions on theblockchain 722 are sequenced and cryptographically linked togetherpreventing tampering with blockchain data without breaking the hashlinks. Furthermore, because of the links, the latest block in theblockchain 722 represents every transaction that has come before it. Theblockchain 722 may be stored on a peer file system (local or attachedstorage), which supports an append-only blockchain workload.

The current state of the blockchain 722 and the distributed ledger 722may be stored in the state database 724. Here, the current state datarepresents the latest values for all keys ever included in the chaintransaction log of the blockchain 722. Chaincode invocations executetransactions against the current state in the state database 724. Tomake these chaincode interactions extremely efficient, the latest valuesof all keys are stored in the state database 724. The state database 724may include an indexed view into the transaction log of the blockchain722, it can therefore be regenerated from the chain at any time. Thestate database 724 may automatically get recovered (or generated ifneeded) upon peer startup, before transactions are accepted.

Endorsing nodes receive transactions from clients and endorse thetransaction based on simulated results. Endorsing nodes hold smartcontracts which simulate the transaction proposals. When an endorsingnode endorses a transaction, the endorsing nodes creates a transactionendorsement which is a signed response from the endorsing node to theclient application indicating the endorsement of the simulatedtransaction. The method of endorsing a transaction depends on anendorsement policy which may be specified within chaincode. An exampleof an endorsement policy is “the majority of endorsing peers mustendorse the transaction”. Different channels may have differentendorsement policies. Endorsed transactions are forward by the clientapplication to ordering service 710.

The ordering service 710 accepts endorsed transactions, orders them intoa block, and delivers the blocks to the committing peers. For example,the ordering service 710 may initiate a new block when a threshold oftransactions has been reached, a timer times out, or another condition.In the example of FIG. 7A, blockchain node 712 is a committing peer thathas received a new data new data block 730 for storage on blockchain720. The first block in the blockchain may be referred to as a genesisblock which includes information about the blockchain, its members, thedata stored therein, etc.

The ordering service 710 may be made up of a cluster of orderers. Theordering service 710 does not process transactions, smart contracts, ormaintain the shared ledger. Rather, the ordering service 710 may acceptthe endorsed transactions and specifies the order in which thosetransactions are committed to the distributed ledger 720. Thearchitecture of the blockchain network may be designed such that thespecific implementation of ‘ordering’ (e.g., Solo, Kafka, BFT, etc.)becomes a pluggable component.

Transactions are written to the distributed ledger 720 in a consistentorder. The order of transactions is established to ensure that theupdates to the state database 724 are valid when they are committed tothe network. Unlike a cryptocurrency blockchain system (e.g., Bitcoin,etc.) where ordering occurs through the solving of a cryptographicpuzzle, or mining, in this example the parties of the distributed ledger720 may choose the ordering mechanism that best suits that network.

When the ordering service 710 initializes a new data block 730, the newdata block 730 may be broadcast to committing peers (e.g., blockchainnodes 711, 712, and 713). In response, each committing peer validatesthe transaction within the new data block 730 by checking to make surethat the read set and the write set still match the current world statein the state database 724. Specifically, the committing peer candetermine whether the read data that existed when the endorserssimulated the transaction is identical to the current world state in thestate database 724. When the committing peer validates the transaction,the transaction is written to the blockchain 722 on the distributedledger 720, and the state database 724 is updated with the write datafrom the read-write set. If a transaction fails, that is, if thecommitting peer finds that the read-write set does not match the currentworld state in the state database 724, the transaction ordered into ablock will still be included in that block, but it will be marked asinvalid, and the state database 724 will not be updated.

Referring to FIG. 7B, a new data block 730 (also referred to as a datablock) that is stored on the blockchain 722 of the distributed ledger720 may include multiple data segments such as a block header 740, blockdata 750 (block data section), and block metadata 760. It should beappreciated that the various depicted blocks and their contents, such asnew data block 730 and its contents, shown in FIG. 7B are merelyexamples and are not meant to limit the scope of the exampleembodiments. In a conventional block, the data section may storetransactional information of N transaction(s) (e.g., 1, 10, 100, 500,1000, 2000, 3000, etc.) within the block data 750.

The new data block 730 may include a link to a previous block (e.g., onthe blockchain 722 in FIG. 7A) within the block header 740. Inparticular, the block header 740 may include a hash of a previousblock's header. The block header 740 may also include a unique blocknumber, a hash of the block data 750 of the new data block 730, and thelike. The block number of the new data block 730 may be unique andassigned in various orders, such as an incremental/sequential orderstarting from zero.

The block metadata 760 may store multiple fields of metadata (e.g., as abyte array, etc.). Metadata fields may include signature on blockcreation, a reference to a last configuration block, a transactionfilter identifying valid and invalid transactions within the block, lastoffset persisted of an ordering service that ordered the block, and thelike. The signature, the last configuration block, and the orderermetadata may be added by the ordering service 710. Meanwhile, acommitter of the block (such as blockchain node 712) may addvalidity/invalidity information based on an endorsement policy,verification of read/write sets, and the like. The transaction filtermay include a byte array of a size equal to the number of transactionsthat are included in the block data 750 and a validation codeidentifying whether a transaction was valid/invalid.

According to various embodiments, the block metadata 760 may also storecommitments to randomness 762 produced/created by member nodes of acurrent consensus committee and encrypted secret shares. For example,the commitments 762 may include the fields of data described in theexamples of FIGS. 4A-4D, and the like.

FIG. 7C illustrates an embodiment of a blockchain 770 for digitalcontent in accordance with the embodiments described herein. The digitalcontent may include one or more files and associated information. Thefiles may include media, images, video, audio, text, links, graphics,animations, web pages, documents, or other forms of digital content. Theimmutable, append-only aspects of the blockchain serve as a safeguard toprotect the integrity, validity, and authenticity of the digitalcontent, making it suitable use in legal proceedings where admissibilityrules apply or other settings where evidence is taken into considerationor where the presentation and use of digital information is otherwise ofinterest. In this case, the digital content may be referred to asdigital evidence.

The blockchain may be formed in various ways. In one embodiment, thedigital content may be included in and accessed from the blockchainitself. For example, each block of the blockchain may store a hash valueof reference information (e.g., header, value, etc.) along theassociated digital content. The hash value and associated digitalcontent may then be encrypted together. Thus, the digital content ofeach block may be accessed by decrypting each block in the blockchain,and the hash value of each block may be used as a basis to reference aprevious

Block 1 Block 2 . . . Block N Hash Value 1 Hash Value 2 Hash Value NDigital Content 1 Digital Content 2 Digital Content N

In one embodiment, the digital content may be not included in theblockchain. For example, the blockchain may store the encrypted hashesof the content of each block without any of the digital content. Thedigital content may be stored in another storage area or memory addressin association with the hash value of the original file. The otherstorage area may be the same storage device used to store the blockchainor may be a different storage area or even a separate relationaldatabase. The digital content of each block may be referenced oraccessed by obtaining or querying the hash value of a block of interestand then looking up that has value in the storage area, which is storedin correspondence with the actual digital content. This operation may beperformed, for example, a database gatekeeper. This may be illustratedas follows:

Blockchain Storage Area Block 1 Hash Value Block 1 Hash Value . . .Content . . . . . . Block N Hash Value Block N Hash Value . . . Content

In the example embodiment of FIG. 7C, the blockchain 770 includes anumber of blocks 778 ₁, 778 ₂, . . . 778 _(N) cryptographically linkedin an ordered sequence, where N≥1. The encryption used to link theblocks 778 ₁, 778 ₂, . . . 778 _(N) may be any of a number of keyed orun-keyed Hash functions. In one embodiment, the blocks 778 ₁, 778 ₂, . .. 778 _(N) are subject to a hash function which produces n-bitalphanumeric outputs (where n is 256 or another number) from inputs thatare based on information in the blocks. Examples of such a hash functioninclude, but are not limited to, a SHA-type (SHA stands for Secured HashAlgorithm) algorithm, Merkle-Damgard algorithm, HAIFA algorithm,Merkle-tree algorithm, nonce-based algorithm, and anon-collision-resistant PRF algorithm. In another embodiment, the blocks778 ₁, 778 ₂, . . . , 778 _(N) may be cryptographically linked by afunction that is different from a hash function. For purposes ofillustration, the following description is made with reference to a hashfunction, e.g., SHA-2.

Each of the blocks 778 ₁, 778 ₂, . . . , 778 _(N) in the blockchainincludes a header, a version of the file, and a value. The header andthe value are different for each block as a result of hashing in theblockchain. In one embodiment, the value may be included in the header.As described in greater detail below, the version of the file may be theoriginal file or a different version of the original file.

The first block 778 ₁ in the blockchain is referred to as the genesisblock and includes the header 772 ₁, original file 774 ₁, and an initialvalue 776 ₁. The hashing scheme used for the genesis block, and indeedin all subsequent blocks, may vary. For example, all the information inthe first block 778 ₁ may be hashed together and at one time, or each ora portion of the information in the first block 778 ₁ may be separatelyhashed and then a hash of the separately hashed portions may beperformed.

The header 772 ₁ may include one or more initial parameters, which, forexample, may include a version number, timestamp, nonce, rootinformation, difficulty level, consensus protocol, duration, mediaformat, source, descriptive keywords, and/or other informationassociated with original file 774 ₁ and/or the blockchain. The header772 ₁ may be generated automatically (e.g., by blockchain networkmanaging software) or manually by a blockchain participant. Unlike theheader in other blocks 778 ₂ to 778 _(N) in the blockchain, the header772 ₁ in the genesis block does not reference a previous block, simplybecause there is no previous block.

The original file 774 ₁ in the genesis block may be, for example, dataas captured by a device with or without processing prior to itsinclusion in the blockchain. The original file 774 ₁ is received throughthe interface of the system from the device, media source, or node. Theoriginal file 774 ₁ is associated with metadata, which, for example, maybe generated by a user, the device, and/or the system processor, eithermanually or automatically. The metadata may be included in the firstblock 778 ₁ in association with the original file 774 ₁.

The value 776 ₁ in the genesis block is an initial value generated basedon one or more unique attributes of the original file 774 ₁. In oneembodiment, the one or more unique attributes may include the hash valuefor the original file 774 ₁, metadata for the original file 774 ₁, andother information associated with the file. In one implementation, theinitial value 776 ₁ may be based on the following unique attributes:

-   -   1) SHA-2 computed hash value for the original file    -   2) originating device ID    -   3) starting timestamp for the original file    -   4) initial storage location of the original file    -   5) blockchain network member ID for software to currently        control the original file and associated metadata

The other blocks 778 ₂ to 778 _(N) in the blockchain also have headers,files, and values. However, unlike the first block 772 ₁, each of theheaders 772 ₂ to 772 _(N) in the other blocks includes the hash value ofan immediately preceding block. The hash value of the immediatelypreceding block may be just the hash of the header of the previous blockor may be the hash value of the entire previous block. By including thehash value of a preceding block in each of the remaining blocks, a tracecan be performed from the Nth block back to the genesis block (and theassociated original file) on a block-by-block basis, as indicated byarrows 780, to establish an auditable and immutable chain-of-custody.

Each of the header 772 ₂ to 772 _(N) in the other blocks may alsoinclude other information, e.g., version number, timestamp, nonce, rootinformation, difficulty level, consensus protocol, and/or otherparameters or information associated with the corresponding files and/orthe blockchain in general.

The files 774 ₂ to 774 _(N) in the other blocks may be equal to theoriginal file or may be a modified version of the original file in thegenesis block depending, for example, on the type of processingperformed. The type of processing performed may vary from block toblock. The processing may involve, for example, any modification of afile in a preceding block, such as redacting information or otherwisechanging the content of, taking information away from, or adding orappending information to the files.

Additionally, or alternatively, the processing may involve merelycopying the file from a preceding block, changing a storage location ofthe file, analyzing the file from one or more preceding blocks, movingthe file from one storage or memory location to another, or performingaction relative to the file of the blockchain and/or its associatedmetadata. Processing which involves analyzing a file may include, forexample, appending, including, or otherwise associating variousanalytics, statistics, or other information associated with the file.

The values in each of the other blocks 776 ₂ to 776 _(N) in the otherblocks are unique values and are all different as a result of theprocessing performed. For example, the value in any one blockcorresponds to an updated version of the value in the previous block.The update is reflected in the hash of the block to which the value isassigned. The values of the blocks therefore provide an indication ofwhat processing was performed in the blocks and also permit a tracingthrough the blockchain back to the original file. This tracking confirmsthe chain-of-custody of the file throughout the entire blockchain.

For example, consider the case where portions of the file in a previousblock are redacted, blocked out, or pixelated in order to protect theidentity of a person shown in the file. In this case, the blockincluding the redacted file will include metadata associated with theredacted file, e.g., how the redaction was performed, who performed theredaction, timestamps where the redaction(s) occurred, etc. The metadatamay be hashed to form the value. Because the metadata for the block isdifferent from the information that was hashed to form the value in theprevious block, the values are different from one another and may berecovered when decrypted.

In one embodiment, the value of a previous block may be updated (e.g., anew hash value computed) to form the value of a current block when anyone or more of the following occurs. The new hash value may be computedby hashing all or a portion of the information noted below, in thisexample embodiment.

-   -   a) new SHA-2 computed hash value if the file has been processed        in any way (e.g., if the file was redacted, copied, altered,        accessed, or some other action was taken) b) new storage        location for the file    -   c) new metadata identified associated with the file    -   d) transfer of access or control of the file from one blockchain        participant to another blockchain participant

FIG. 7D illustrates an embodiment of a block which may represent thestructure of the blocks in the blockchain 790 in accordance with oneembodiment. The block, Block_(i), includes a header 772 _(i), a file 774_(i), and a value 776 _(i).

The header 772 _(i) includes a hash value of a previous blockBlock_(i−1) and additional reference information, which, for example,may be any of the types of information (e.g., header informationincluding references, characteristics, parameters, etc.) discussedherein. All blocks reference the hash of a previous block except, ofcourse, the genesis block. The hash value of the previous block may bejust a hash of the header in the previous block or a hash of all or aportion of the information in the previous block, including the file andmetadata.

The file 774 _(i) includes a plurality of data, such as Data 1, Data 2,. . . , Data N in sequence. The data are tagged with Metadata 1,Metadata 2, . . . , Metadata N which describe the content and/orcharacteristics associated with the data. For example, the metadata foreach data may include information to indicate a timestamp for the data,process the data, keywords indicating the persons or other contentdepicted in the data, and/or other features that may be helpful toestablish the validity and content of the file as a whole, andparticularly its use a digital evidence, for example, as described inconnection with an embodiment discussed below. In addition to themetadata, each data may be tagged with reference REF₁, REF₂, . . . ,REF_(N) to a previous data to prevent tampering, gaps in the file, andsequential reference through the file.

Once the metadata is assigned to the data (e.g., through a smartcontract), the metadata cannot be altered without the hash changing,which can easily be identified for invalidation. The metadata, thus,creates a data log of information that may be accessed for use byparticipants in the blockchain.

The value 776 _(i) is a hash value or other value computed based on anyof the types of information previously discussed. For example, for anygiven block Block_(i), the value for that block may be updated toreflect the processing that was performed for that block, e.g., new hashvalue, new storage location, new metadata for the associated file,transfer of control or access, identifier, or other action orinformation to be added. Although the value in each block is shown to beseparate from the metadata for the data of the file and header, thevalue may be based, in part or whole, on this metadata in anotherembodiment.

Once the blockchain 770 is formed, at any point in time, the immutablechain-of-custody for the file may be obtained by querying the blockchainfor the transaction history of the values across the blocks. This query,or tracking procedure, may begin with decrypting the value of the blockthat is most currently included (e.g., the last (N^(th)) block), andthen continuing to decrypt the value of the other blocks until thegenesis block is reached and the original file is recovered. Thedecryption may involve decrypting the headers and files and associatedmetadata at each block, as well.

Decryption is performed based on the type of encryption that took placein each block. This may involve the use of private keys, public keys, ora public key-private key pair. For example, when asymmetric encryptionis used, blockchain participants or a processor in the network maygenerate a public key and private key pair using a predeterminedalgorithm. The public key and private key are associated with each otherthrough some mathematical relationship. The public key may bedistributed publicly to serve as an address to receive messages fromother users, e.g., an IP address or home address. The private key iskept secret and used to digitally sign messages sent to other blockchainparticipants. The signature is included in the message so that therecipient can verify using the public key of the sender. This way, therecipient can be sure that only the sender could have sent this message.

Generating a key pair may be analogous to creating an account on theblockchain, but without having to actually register anywhere. Also,every transaction that is executed on the blockchain is digitally signedby the sender using their private key. This signature ensures that onlythe owner of the account can track and process (if within the scope ofpermission determined by a smart contract) the file of the blockchain.

FIGS. 8A and 8B illustrate additional examples of use cases forblockchain which may be incorporated and used herein. In particular,FIG. 8A illustrates an example 800 of a blockchain 810 which storesmachine learning (artificial intelligence) data. Machine learning relieson vast quantities of historical data (or training data) to buildpredictive models for accurate prediction on new data. Machine learningsoftware (e.g., neural networks, etc.) can often sift through millionsof records to unearth non-intuitive patterns.

In the example of FIG. 8A, a host platform 820 builds and deploys amachine learning model for predictive monitoring of assets 830. Here,the host platform 820 may be a cloud platform, an industrial server, aweb server, a personal computer, a user device, and the like. Assets 830can be any type of asset (e.g., machine or equipment, etc.) such as anaircraft, locomotive, turbine, medical machinery and equipment, oil andgas equipment, boats, ships, vehicles, and the like. As another example,assets 830 may be non-tangible assets such as stocks, currency, digitalcoins, insurance, or the like.

The blockchain 810 can be used to significantly improve both a trainingprocess 802 of the machine learning model and a predictive process 804based on a trained machine learning model. For example, in 802, ratherthan requiring a data scientist/engineer or other user to collect thedata, historical data may be stored by the assets 830 themselves (orthrough an intermediary, not shown) on the blockchain 810. This cansignificantly reduce the collection time needed by the host platform 820when performing predictive model training. For example, using smartcontracts, data can be directly and reliably transferred straight fromits place of origin to the blockchain 810. By using the blockchain 810to ensure the security and ownership of the collected data, smartcontracts may directly send the data from the assets to the individualsthat use the data for building a machine learning model. This allows forsharing of data among the assets 830.

The collected data may be stored in the blockchain 810 based on aconsensus mechanism. The consensus mechanism pulls in (permissionednodes) to ensure that the data being recorded is verified and accurate.The data recorded is time-stamped, cryptographically signed, andimmutable. It is therefore auditable, transparent, and secure. AddingIoT devices which write directly to the blockchain can, in certain cases(i.e. supply chain, healthcare, logistics, etc.), increase both thefrequency and accuracy of the data being recorded.

Furthermore, training of the machine learning model on the collecteddata may take rounds of refinement and testing by the host platform 820.Each round may be based on additional data or data that was notpreviously considered to help expand the knowledge of the machinelearning model. In 802, the different training and testing steps (andthe data associated therewith) may be stored on the blockchain 810 bythe host platform 820. Each refinement of the machine learning model(e.g., changes in variables, weights, etc.) may be stored on theblockchain 810. This provides verifiable proof of how the model wastrained and what data was used to train the model. Furthermore, when thehost platform 820 has achieved a finally trained model, the resultingmodel may be stored on the blockchain 810.

After the model has been trained, it may be deployed to a liveenvironment where it can make predictions/decisions based on theexecution of the final trained machine learning model. For example, in804, the machine learning model may be used for condition-basedmaintenance (CBM) for an asset such as an aircraft, a wind turbine, ahealthcare machine, and the like. In this example, data fed back fromthe asset 830 may be input the machine learning model and used to makeevent predictions such as failure events, error codes, and the like.Determinations made by the execution of the machine learning model atthe host platform 820 may be stored on the blockchain 810 to provideauditable/verifiable proof. As one non-limiting example, the machinelearning model may predict a future breakdown/failure to a part of theasset 830 and create alert or a notification to replace the part. Thedata behind this decision may be stored by the host platform 820 on theblockchain 810. In one embodiment the features and/or the actionsdescribed and/or depicted herein can occur on or with respect to theblockchain 810.

New transactions for a blockchain can be gathered together into a newblock and added to an existing hash value. This is then encrypted tocreate a new hash for the new block. This is added to the next list oftransactions when they are encrypted, and so on. The result is a chainof blocks that each contain the hash values of all preceding blocks.Computers that store these blocks regularly compare their hash values toensure that they are all in agreement. Any computer that does not agree,discards the records that are causing the problem. This approach is goodfor ensuring tamper-resistance of the blockchain, but it is not perfect.

One way to game this system is for a dishonest user to change the listof transactions in their favor, but in a way that leaves the hashunchanged. This can be done by brute force, in other words by changing arecord, encrypting the result, and seeing whether the hash value is thesame. And if not, trying again and again and again until it finds a hashthat matches. The security of blockchains is based on the belief thatordinary computers can only perform this kind of brute force attack overtime scales that are entirely impractical, such as the age of theuniverse. By contrast, quantum computers are much faster (1000s of timesfaster) and consequently pose a much greater threat.

FIG. 8B illustrates an example 850 of a quantum-secure blockchain 852which implements quantum key distribution (QKD) to protect against aquantum computing attack. In this example, blockchain users can verifyeach other's identities using QKD. This sends information using quantumparticles such as photons, which cannot be copied by an eavesdropperwithout destroying them. In this way, a sender and a receiver throughthe blockchain can be sure of each other's identity.

In the example of FIG. 8B, four users are present 854, 856, 858, and860. Each of pair of users may share a secret key 862 (i.e., a QKD)between themselves. Since there are four nodes in this example, sixpairs of nodes exists, and therefore six different secret keys 862 areused including QKD_(AB), QKD_(AC), QKD_(AD), QKD_(BC), QKD_(BD), andQKD_(CD). Each pair can create a QKD by sending information usingquantum particles such as photons, which cannot be copied by aneavesdropper without destroying them. In this way, a pair of users canbe sure of each other's identity.

The operation of the blockchain 852 is based on two procedures (i)creation of transactions, and (ii) construction of blocks that aggregatethe new transactions. New transactions may be created similar to atraditional blockchain network. Each transaction may contain informationabout a sender, a receiver, a time of creation, an amount (or value) tobe transferred, a list of reference transactions that justifies thesender has funds for the operation, and the like. This transactionrecord is then sent to all other nodes where it is entered into a poolof unconfirmed transactions. Here, two parties (i.e., a pair of usersfrom among 854-860) authenticate the transaction by providing theirshared secret key 862 (QKD). This quantum signature can be attached toevery transaction making it exceedingly difficult to tamper with. Eachnode checks their entries with respect to a local copy of the blockchain852 to verify that each transaction has sufficient funds. However, thetransactions are not yet confirmed.

Rather than perform a traditional mining process on the blocks, theblocks may be created in a decentralized manner using a broadcastprotocol. At a predetermined period of time (e.g., seconds, minutes,hours, etc.) the network may apply the broadcast protocol to anyunconfirmed transaction thereby to achieve a Byzantine agreement(consensus) regarding a correct version of the transaction. For example,each node may possess a private value (transaction data of thatparticular node). In a first round, nodes transmit their private valuesto each other. In subsequent rounds, nodes communicate the informationthey received in the previous round from other nodes. Here, honest nodesare able to create a complete set of transactions within a new block.This new block can be added to the blockchain 852. In one embodiment thefeatures and/or the actions described and/or depicted herein can occuron or with respect to the blockchain 852.

FIG. 9 illustrates an example system 900 that supports one or more ofthe example embodiments described and/or depicted herein. The system 900comprises a computer system/server 902, which is operational withnumerous other general purpose or special purpose computing systemenvironments or configurations. Examples of well-known computingsystems, environments, and/or configurations that may be suitable foruse with computer system/server 902 include, but are not limited to,personal computer systems, server computer systems, thin clients, thickclients, hand-held or laptop devices, multiprocessor systems,microprocessor-based systems, set top boxes, programmable consumerelectronics, network PCs, minicomputer systems, mainframe computersystems, and distributed cloud computing environments that include anyof the above systems or devices, and the like.

Computer system/server 902 may be described in the general context ofcomputer system-executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 902 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 9 , computer system/server 902 in cloud computing node900 is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 902 may include, but are notlimited to, one or more processors or processing units 904, a systemmemory 906, and a bus that couples various system components includingsystem memory 906 to processor 904.

The bus represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. By way of example, and notlimitation, such architectures include Industry Standard Architecture(ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA)bus, Video Electronics Standards Association (VESA) local bus, andPeripheral Component Interconnects (PCI) bus.

Computer system/server 902 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 902, and it includes both volatileand non-volatile media, removable and non-removable media. System memory906, in one embodiment, implements the flow diagrams of the otherfigures. The system memory 906 can include computer system readablemedia in the form of volatile memory, such as random-access memory (RAM)910 and/or cache memory 912. Computer system/server 902 may furtherinclude other removable/non-removable, volatile/non-volatile computersystem storage media. By way of example only, storage system 914 can beprovided for reading from and writing to a non-removable, non-volatilemagnetic media (not shown and typically called a “hard drive”). Althoughnot shown, a magnetic disk drive for reading from and writing to aremovable, non-volatile magnetic disk (e.g., a “floppy disk”), and anoptical disk drive for reading from or writing to a removable,non-volatile optical disk such as a CD-ROM, DVD-ROM or other opticalmedia can be provided. In such instances, each can be connected to thebus by one or more data media interfaces. As will be further depictedand described below, memory 906 may include at least one program producthaving a set (e.g., at least one) of program modules that are configuredto carry out the functions of various embodiments of the application.

Program/utility 916, having a set (at least one) of program modules 918,may be stored in memory 906 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 918 generally carry out the functionsand/or methodologies of various embodiments of the application asdescribed herein.

As will be appreciated by one skilled in the art, aspects of the presentapplication may be embodied as a system, method, or computer programproduct. Accordingly, aspects of the present application may take theform of an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present application may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Computer system/server 902 may also communicate with one or moreexternal devices 920 such as a keyboard, a pointing device, a display922, etc.; one or more devices that enable a user to interact withcomputer system/server 902; and/or any devices (e.g., network card,modem, etc.) that enable computer system/server 902 to communicate withone or more other computing devices. Such communication can occur viaI/O interfaces 924. Still yet, computer system/server 902 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 926. As depicted, network adapter 926communicates with the other components of computer system/server 902 viaa bus. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 902. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

Although an exemplary embodiment of at least one of a system, method,and non-transitory computer readable medium has been illustrated in theaccompanied drawings and described in the foregoing detaileddescription, it will be understood that the application is not limitedto the embodiments disclosed, but is capable of numerous rearrangements,modifications, and substitutions as set forth and defined by thefollowing claims. For example, the capabilities of the system of thevarious figures can be performed by one or more of the modules orcomponents described herein or in a distributed architecture and mayinclude a transmitter, receiver or pair of both. For example, all orpart of the functionality performed by the individual modules, may beperformed by one or more of these modules. Further, the functionalitydescribed herein may be performed at various times and in relation tovarious events, internal or external to the modules or components. Also,the information sent between various modules can be sent between themodules via at least one of: a data network, the Internet, a voicenetwork, an Internet Protocol network, a wireless device, a wired deviceand/or via plurality of protocols. Also, the messages sent or receivedby any of the modules may be sent or received directly and/or via one ormore of the other modules.

One skilled in the art will appreciate that a “system” could be embodiedas a personal computer, a server, a console, a personal digitalassistant (PDA), a cell phone, a tablet computing device, a smartphoneor any other suitable computing device, or combination of devices.Presenting the above-described functions as being performed by a“system” is not intended to limit the scope of the present applicationin any way but is intended to provide one example of many embodiments.Indeed, methods, systems and apparatuses disclosed herein may beimplemented in localized and distributed forms consistent with computingtechnology.

It should be noted that some of the system features described in thisspecification have been presented as modules, in order to moreparticularly emphasize their implementation independence. For example, amodule may be implemented as a hardware circuit comprising custom verylarge-scale integration (VLSI) circuits or gate arrays, off-the-shelfsemiconductors such as logic chips, transistors, or other discretecomponents. A module may also be implemented in programmable hardwaredevices such as field programmable gate arrays, programmable arraylogic, programmable logic devices, graphics processing units, or thelike.

A module may also be at least partially implemented in software forexecution by various types of processors. An identified unit ofexecutable code may, for instance, comprise one or more physical orlogical blocks of computer instructions that may, for instance, beorganized as an object, procedure, or function. Nevertheless, theexecutables of an identified module need not be physically locatedtogether but may comprise disparate instructions stored in differentlocations which, when joined logically together, comprise the module andachieve the stated purpose for the module. Further, modules may bestored on a computer-readable medium, which may be, for instance, a harddisk drive, flash device, random access memory (RAM), tape, or any othersuch medium used to store data.

Indeed, a module of executable code could be a single instruction, ormany instructions, and may even be distributed over several differentcode segments, among different programs, and across several memorydevices. Similarly, operational data may be identified and illustratedherein within modules and may be embodied in any suitable form andorganized within any suitable type of data structure. The operationaldata may be collected as a single data set or may be distributed overdifferent locations including over different storage devices, and mayexist, at least partially, merely as electronic signals on a system ornetwork.

It will be readily understood that the components of the application, asgenerally described and illustrated in the figures herein, may bearranged and designed in a wide variety of different configurations.Thus, the detailed description of the embodiments is not intended tolimit the scope of the application as claimed but is merelyrepresentative of selected embodiments of the application.

One having ordinary skill in the art will readily understand that theabove may be practiced with steps in a different order, and/or withhardware elements in configurations that are different than those whichare disclosed. Therefore, although the application has been describedbased upon these preferred embodiments, it would be apparent to those ofskill in the art that certain modifications, variations, and alternativeconstructions would be apparent.

While preferred embodiments of the present application have beendescribed, it is to be understood that the embodiments described areillustrative only and the scope of the application is to be definedsolely by the appended claims when considered with a full range ofequivalents and modifications (e.g., protocols, hardware devices,software platforms etc.) thereto.

What is claimed is:
 1. An apparatus comprising: a memory configured tostore blockchain blocks committed to a blockchain based on a protocolexecuted by a current consensus committee of a blockchain network; and aprocessor configured to receive random values from the blockchain blockswhich are created by nodes of the current consensus committee; randomlydetermine nodes of a next consensus committee of the blockchain networkwith respect to the current consensus committee based on the randomvalues created by the nodes of the current consensus committee, andstore a new block to the blockchain in memory based on a protocolexecuted by the nodes of the next consensus committee.
 2. The apparatusof claim 1, wherein the current consensus committee and the nextconsensus committee comprise different respective subsets of nodes fromamong a larger set of nodes included in the blockchain network.
 3. Theapparatus of claim 1, wherein the blockchain blocks comprise firstbornblocks created by the nodes of the current consensus committee.
 4. Theapparatus of claim 1, wherein the processor is further configured todetect a committee change notification within a last block produced bythe current consensus committee, and randomly determine the nodes of thenext consensus committee in response to detection of the committeechange notification.
 5. The apparatus of claim 1, wherein the randomvalues comprise randomly sampled coefficients from a polynomialequation.
 6. The apparatus of claim 1, wherein the random values areencrypted, and the processor is further configured to receive and verifyzero-knowledge proofs (ZKPs) from the nodes of the current consensuscommittee that prove correctness of the encryption of the random values.7. The apparatus of claim 1, wherein the processor is configured tocombine the random values created by the nodes of the current consensuscommittee into a random seed, and map segments of the random seed tonode identifiers of the nodes in the next consensus committee.
 8. Theapparatus of claim 1, wherein the processor is configured to receive therandom values piggybacked via pre-prepare messages, respectively, of thenodes of the current consensus committee.
 9. A method comprising:storing blockchain blocks committed to a blockchain based on a protocolexecuted by a current consensus committee of a blockchain network;receiving random values from the blockchain blocks which are created bynodes of the current consensus committee; determining nodes of a nextconsensus committee of the blockchain network with respect to thecurrent consensus committee based on the random values created by thenodes of the current consensus committee; and storing a new block to theblockchain based on a protocol executed by the nodes of the nextconsensus committee.
 10. The method of claim 9, wherein the currentconsensus committee and the next consensus committee comprise differentrespective subsets of nodes from among a larger set of nodes included inthe blockchain network.
 11. The method of claim 9, wherein theblockchain blocks include firstborn blocks created by the nodes of thecurrent consensus committee.
 12. The method of claim 9, wherein themethod further comprises detecting a committee change notificationwithin a last block produced by the current consensus committee, whereinthe randomly determining is performed in response to the detecting. 13.The method of claim 9, wherein the random values comprise randomlysampled coefficients from a polynomial equation.
 14. The method of claim9, wherein the random values are encrypted, and the receiving furthercomprises receiving zero-knowledge proofs (ZKPs) from the nodes of thecurrent consensus committee proving correctness of the encryption of therandom values.
 15. The method of claim 9, wherein the randomlydetermining comprises combining the random values created by the nodesof the current consensus committee into a random seed, and mappingsegments of the random seed to node identifiers of the nodes in the nextconsensus committee.
 16. The method of claim 9, wherein the receivingthe random values comprises receiving the random values piggybacked viapre-prepare messages, respectively, of the nodes of the currentconsensus committee.
 17. A non-transitory computer-readable mediumcomprising instructions which when executed by a processor cause theprocessor to perform a method comprising: storing blockchain blockscommitted to a blockchain based on a protocol executed by a currentconsensus committee of a blockchain network; receiving random valuesfrom the blockchain blocks which are created by nodes of the currentconsensus committee; randomly determining nodes of a next consensuscommittee of the blockchain network with respect to the currentconsensus committee based on the random values created by the nodes ofthe current consensus committee; and storing a new block to theblockchain based on a protocol executed by the nodes of the nextconsensus committee.
 18. The non-transitory computer-readable medium ofclaim 17, wherein the current consensus committee and the next consensuscommittee comprise different respective subsets of nodes from among alarger set of nodes included in the blockchain network.
 19. Thenon-transitory computer-readable medium of claim 17, wherein theblockchain blocks comprise firstborn blocks created by the nodes of thecurrent consensus committee.
 20. The non-transitory computer-readablemedium of claim 17, wherein the method further comprises detecting acommittee change notification within a last block produced by thecurrent consensus committee, wherein the randomly determining isperformed in response to the detecting.